Servo system control in digital video disc (DVD)

The storage capacity of a DVD is at least 8 times that of a compact disc (CD) with the same disc size. However, the higher density has led to narrower tracks and pitches (distances between tracks). This requires an improvement of the follow-up capability within limits which are not detrimental to its stability and speed of the system. In this paper, some techniques pertaining to the DVD servo control system, which are critical but not identical to the CD-ROM system are reviewed and investigated. These include the one-beam push-pull tracking method used in tracking error generation, adaptive learning control algorithm for DVD pickup spindle motor tracking, and variable speed control of the turntable brushless DC motor.